Many different embodiments of this type of quick-change device have become known.
A first embodiment of a quick-change device is known from, for example, EP 0 483 232 B1 and consists of a quick changer, comprising a pivoting and locking device, and an adapter. The quick changer is assigned to the arm of the excavator, and the opposing adapter, which is to be connected to the quick changer, is mounted on an exchangeable tool such as a sorting bucket.
The pivoting and locking device described in the publication cited above locks the adapter and the quick changer together, but it also brings the hydraulic couplings for the hydraulic fluid together. To bring these hydraulic couplings together, they must be pivoted over a relatively long distance. As a result of the spreading forces which occur during operation, the hydraulic couplings can leak and ultimately fail. This can also lead to considerable environmental damage.
A quick-change device is also known from WO 2005/093172 A1, which executes a pivoting movement to connect the quick changer to the adapter and also to connect the two coupling blocks together. The coupling blocks are mounted on the free end opposite the pivot axis, and one of the coupling blocks is supported in a floating manner. To counteract the spreading forces, a device is provided which generates hydraulic pressure on the hydraulic coupling in such a way that the coupling can resist the spreading forces. The force acts essentially in a direction perpendicular to the contact surfaces between the coupling blocks. Relative movements based on the elasticity of the selected material or on the basis of the floating support are thus avoided. In addition, a reliable hydraulic connection is guaranteed during operation.
The problem with this design, however, is that, in certain types of applications, the hydraulic pressures are very high, and these therefore cause very high spreading forces. Considerable effort is therefore required to counteract these spreading forces by means of a hydraulically produced pressure.
A quick-change device of the general type in question is also known from DE 101 59 417 A1. Here the coupling blocks of the hydraulic coupling are held positively in position by hooks, which are supported on one of the coupling blocks and which engage with a pin on the other coupling block when in the operating position.
It has been found, however, that, when the spreading forces are very high, either the mechanical means undergo fatigue and break or the material creeps, which causes the mechanical means to jam. As a result, the hydraulic coupling can no longer be disconnected, and, depending on the embodiment, the quick changer is also blocked.